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Comet Assay

The Comet Assay, also called single cell gel electrophoresis, is a rapid and sensitive technique for accurately analyzing DNA damage (genotoxicity) in individual cells from small molecule formulations of industrial chemicals, consumer products, agrochemicals, emission particulates, and pharmaceuticals. The Comet Assay is a common follow up to a positive in vitro assay (such as the chromosome aberration, mouse lymphoma and/or in-vitro micronucleus assay). As per the ICH recommendations, the comet assay combined with micronucleus assay can be performed as part of the initial test battery after performing the Ames assay.

At BioReliance, we offer Comet assays in multiple formats including:

In vitro Comet assays (numerous cell line options available)

Comet assay is available for Biomonitoring in human blood and bone marrow samples

In vivo rodent Comet assays (different dosing regimens are available)

In vivo Comet assay in combination with in vivo Micronucleus assay

Comet assay slide evaluations (if the assay is performed at your lab and the slides need to be scored)

Mobile Comet – we bring the assay to you and can perform in any lab as part of an on going toxicology study!

Comet Assay BasicsThe Comet Assay can be used to detect multiple types of DNA damage that are caused by a small molecule test agent. This includes single and double stranded breaks, alkali labile sites, oxidative base damage, and DNA cross-linking.

Cells are embedded in a thin, low-melting-point agarose suspension on a microscope slide; thus the name ‘single cell gel electrophoresis’. Cells are then lysed in an alkaline pH buffer to remove cellular proteins and allow for DNA unwinding. The lysed cells are run on gel electrophoresis to separate nucleic acid by size and charge. This is followed by visual analysis with DNA staining with Sybrgold™ to determine the extent of DNA damage.

The resulting image that is obtained resembles a comet with a distinct head and tail. The head is composed of intact DNA, while the tail consists of damaged (single-strand or double-strand breaks) or broken pieces of DNA. The extent of DNA damage is directly proportional to the intensity of the tail or % tail DNA.

The Comet assay can detect specific DNA damage and repair, and thus can explore mechanism and mode of action to further investigate the effects of a compound.BioReliance is a member of the JaCVAM Comet Validation project and OECD Expert Working Group for development of the Comet Assay guideline, and has performed hundreds of Comet Assays for genotoxicity testing.